Investment Calculator

Calculate growth, compounding and the tax due on the return from your investment.

Investment

Starting amount

Annual return

Term

years

Growth method

Compound interest Simple interest

Compounding

Regular contribution optional

Contribution frequency

Deductions & fees

Add service fees, platform charges, performance fees or other deductions. You can use a fixed amount or percentage and choose when it is taken.

No deductions added.

Deductions reduce the projected investment value. The calculator does not automatically assume a fee is deductible for tax purposes, because HMRC treatment depends on the exact charge and investment.

Tax & investment type

First choose the account or tax wrapper. Then choose what the money is actually invested in. This lets the calculator apply the right UK tax treatment without mixing up an ISA with the investment held inside it.

1. Where is the investment held?

2. What is the money invested in?

Your Income Tax band Used when this investment produces taxable interest or dividends.

Taxable income before this capital gain

Enter taxable income after your Personal Allowance and Income Tax reliefs. This lets the calculator split taxable gains between the 18% and 24% CGT rates.

Income share of projected return

Used to separate income from capital growth.

When is the interest paid or made available? Savings tax normally follows when interest is received or made available.

Lifetime ISA withdrawal The starting amount is treated as an existing LISA balance. Regular contributions receive the 25% government bonus, subject to the annual LISA limit.

Final pot before tax£0.00

Total paid in£0.00

Gross growth£0.00

Deductions£0.00

Estimated tax£0.00

Net gain after tax & fees£0.00

How the tax is shown: deductions are taken from the projected pot at the point you choose. Estimated tax remains a separate liability and is only deducted in the “Equivalent value after estimated tax” figure.

Year	Opening pot	Paid in	Growth	Deductions	Estimated tax due	Closing pot before tax

UK tax references, current 2026/27 rules: ISAs · LISA · Pensions · Savings · Dividends · CGT · Gilts · Corporate bonds · UK bullion coins · Crypto